There is a liquid electrolyte composition comprising: i) a magnesium salt comprising a trifluoromethane sulfonate anion; ii) an additive comprising an organic halide salt, an inorganic halide salt or a mixture thereof; and iii) a solvent comprising one or more ethers, wherein the organic halide salt comprises a halide anion and a cation selected from an optionally substituted quaternary ammonium or a three to nine membered N-heterocyclic cation, and the cation comprises at least one protonated nitrogen capable of dissociating the trifluoromethane sulfonate anion from the magnesium salt, and wherein the total concentration of cations of the inorganic halide salt and magnesium ions of the magnesium salt divided by the concentration of anions of the inorganic halide salt is greater than 1 in the electrolyte composition. There is further provided an electrochemical cell comprising a) a positive electrode; b) a magnesium negative electrode; and c) the electrolyte composition as described herein, wherein the positive electrode and the magnesium negative electrode are in fluid communication with the electrolyte.

Provided are a member for a sodium-ion secondary battery and a sodium-ion secondary battery both of which are not susceptible to deterioration of charge/discharge cycle characteristics due to charge and discharge. A member 8 for a sodium-ion secondary battery includes: a solid electrolyte layer 2 having sodium-ion conductivity; a metallic sodium layer 6 disposed on one principal surface 2b of the solid electrolyte layer 2 and made of metallic sodium; and a metallic layer 5 provided between the solid electrolyte layer 2 and the metallic sodium layer 6 and made of a metal different from the metallic sodium.

Electric batteries wherein the positively charged electrode contacts an aqueous layer containing material which is reduced during electric discharge and/or metal ions are transported through special electrolyte that inhibits dendritic deposition on the negatively charged electrode. Methods described include electrolyte compositions including organoborate anions and cations with low charge density, and aqueous solutions containing bromate and/or bromide anions and high concentrations of dissolved salts.

An electropositive metal electrode coated by an ion-selective conformable polymer provides the negative electrode and the solid-state electrolyte for a rechargeable bi-electrolyte displacement battery that further includes a molten salt electrolyte having a melting temperature below 140° C. interposed between the conformable polymer coating and a positive electrode. Suitable electropositive metals include lithium, sodium, magnesium, and aluminum and the molten salt incorporates a soluble salt of the metal of the negative electrode. Positive electrodes may incorporate metals including Fe, Ni, Bi, Pb, Zn, Sn, and Cu, and thanks to the ion-selective conformable solid-state electrolyte the molten salt is able to incorporate a soluble salt of the metal of the positive electrode. The conformable polymer-coated electropositive metal electrode may be manufactured by a process involving electroplating electropositive metal through a conformable polymer-coated conductive substrate. The conformable polymer-coated conductive substrate may be prepared by coating the conductive substrate in a conformable polymer solution followed by evaporating the solvent. Alternatively, an electropositive metal electrode may be coated directly with the conformable polymer.

The present disclosure relates to an electrolyte comprising: a) a sodium salt; b) an additive comprising at least one additional metallic/metalloid cation having a standard reduction potential which is at least 2.5V more positive than that of sodium cation; wherein said sodium salt and said additive are dispersed in a solvent comprising at least one alkyl carbonate, and wherein the concentration of said metallic/metalloid cation in the electrolyte is 15 mM to 250 mM. The present disclosure also relates to a sodium-sulfur cell comprising a sodium anode, a microporous sulfur cathode, and the electrolyte as described herein. The present disclosure further provides a method of improving cycling life of a sodium-sulfur cell, wherein the sodium-sulfur cell comprising a sodium anode, a sulfur cathode, and an electrolyte containing a sodium salt dispersed in an alkyl carbonate solvent.

Provided is a bipolar all-solid-state sodium ion secondary battery that can increase the voltage without impairing safety. A bipolar all-solid-state sodium ion secondary battery includes: a plurality of all-solid-state sodium ion secondary batteries 1 in each of which a positive electrode layer 3 capable of absorbing and releasing sodium, a solid electrolyte layer 4 made of a sodium ion-conductive oxide, and a negative electrode layer 5 capable of absorbing and releasing sodium are laid one upon another in this order; and a current collector layer 2 provided between the positive electrode layer 3 of each of the plurality of all-solid-state sodium ion secondary batteries 1 and the negative electrode layer 5 of the adjacent all-solid-state sodium ion secondary battery 1 and shared by the positive electrode layer 3 and the negative electrode layer 5.

Systems, articles, and methods directed to electrochemical systems (e.g., batteries) and the electrochemical reduction of halogenated compounds are generally described. In certain embodiments, the halogenated compound comprises at least one sulfur pentahalide (e.g., pentafluoride) group associated with a conjugated system.

The invention relates to alkaline secondary batteries. The secondary battery contains a cathode, an anode and an electrolyte, said secondary battery being arranged between the cathode and anode and comprises an alkali metal ion conductive contact to the cathode and to the carbon layer of the anode. The anode contains or consists of a carbon layer, whereby the carbon layer, alone or in combination with an electrically conductive substrate, forms with an electrically conductive contact.

The present disclosure relates to chemical treatments for preparing metal electrodes, including ex-situ chemical treatments for preparing metal electrodes and to ex-situ chemically treated metal electrodes, which can be used in electrochemical cells. The present disclosure also relates to methods for forming a metal fluoride-based layer (e.g. a SEI fluoride layer) on a metal or an electrode thereof comprising an ex-situ chemical treatment of the metal or electrode thereof, and to electrochemical cells comprising the ex-situ chemically treated metal electrodes.

A solid-state ion conductor includes a compound of the formula Na.sub.xM.sup.1.sub.2−(y+z)M.sup.2.sub.yM.sup.3.sub.z(AO.sub.4).sub.3 wherein M.sup.1, M.sup.2, and M.sup.3 are each independently Hf, Mg, Sc, In, Y, Ca, or Zr; A is P, Si, S, or a combination thereof; 3≤x≤3.5; 0.5≤y≤1; and 0≤z≤0.5. The solid-state ion conductor can be useful in various components of an electrochemical cell.